To me, that's actually rotating the first string BACKWARDS, not forward... But other than that, the exercise is nice.. :)

The problem simply asks for the biggest sum of x ammount of numbers under a certain value. The story makes absolutely no sense, since you wouldn't have ALL the distance options from every city, and hence in reality you couldn't pick random distances (unless you had the option of teletransporting from town to town).

Really think about it, the story here makes no practical sense..

Nice story!

Absolutely silly.. You've worked it out only to give the answers, instead of actually solving it!! :P

To return a function, you simply... return a function!! :)

For example:

function MagicFunction(...a) {
  function toBeReturned(...a) {
    do {
      // this code...
    } while (somethingIsTrue);
    return something;
  }

  return toBeReturned;    // This is how to return a function..
  return toBeReturned();  // This would be, instead, returning a function invocation..
}

I've written this answer based on another one I saw, to prove that the test is wrong. This solution actually FAILS to verify all Leap Years!!!!

Well, this solution is wrong, yes.. But actually the year 2000 IS a leap year, because it is multiple of 400..

;)